Bicycle wheels and rims therefor have been in use for well over a century. Heretofore, most bicycle rims have been made of steel or aluminum. However, in the past few decades, some bicycle rim manufacturers have begun to produce bicycle rims from other materials, such as fiber reinforced plastics (FRPs), including carbon fiber, fiberglass, and nylon fibers, that are mixed in a resin such as epoxy-based resins, phenolic-based resins and/or ester-based resins. Of these composite rims, some have been comprised entirely of FRP composite materials (“full composite wheels”), whereas others have incorporated components of different materials in addition to FRP composites (“multi-component rims”).
An example of a full carbon fiber composite rim is shown in Hed and Haug, U.S. Pat. No. 5,061,013. Other examples of bicycle wheel rims made entirely of a composite material are the ZIPP® 245 and 280 rims, and the ZIPP® 330 and 360 rims, that are available from the assignee of the instant application, Compositech, Inc. of 1180 North Main Street, Speedway, Ind. 46224.
Although full composite wheels represent the current state-of-the-art in high-tech bicycle rims because of their strength, their light-weight and their aerodynamically efficient profiles, bicycle rims made entirely of FRP composites are not well suited to all uses. In particular, one difficulty with known full composite bicycle rims, is that it is difficult to form a full FRP composite fiber rim that will accept standard beaded bicycle tires. Rather, most completely FRP composite wheels are designed for use with “sew up” tires that are actually glued to the rim.
In view of the limitations of full FRP composite rims, multi component rims have been produced that contain both an FRP composite component and a metallic component. An example of such a rim is shown in Sargent U.S. Pat. No. 5,975,645 (the '645 patent rim”), which patent is also assigned to Compositech, Inc., the assignee of the present invention. The '645 patent rim includes a deep drawn structural carbon fiber body composite that provides strength and a favorable aerodynamic profile to the rim. An aluminum tire-engaging hoop rim is coupled to the radially outwardly facing surface of the carbon fiber body portion. The aluminum tire-engaging hoop includes a pair of lips for engaging the beads of a conventional bicycle tire.
Although the '645 rim has proven to be a valuable addition to the assignee's product line, and has been well received by the Applicant's customers, room for improvement still exists.
In particular, one area where room for improvement exists relates to the manner in which the metal hoop is constructed and attached to the carbon fiber rim body. The aluminum hoops for rims produced by the assignee, Compositech, Inc Prior to the instant invention, that were most similar to those shown in the '645 patent were created by forming a generally linear section, that was cut to a size generally equal to the finished circumference of the hoop. The hoop was then bent into its circular-hoop shape, until the first and second ends of the formerly linear section were placed adjacent to each other. The two ends of the hoop were then clamped together. This method of manufacturing the hoop has the disadvantage of leaving a slight gap in the hoop where the first and second ends of the hoop are joined together. It was found by Applicants that this gap created between the two former ends of the aluminum hoop resulted in a rim that, although having fine performance characteristics, was difficult to manufacture, and which was still subject to improvement in its longevity.
It is therefore one object of the present invention to produce an FRP based bicycle rim having a metal rim attached thereto that improves upon the prior known '645 patent rim and other prior art rims by creating a wheel with no discontinuity in the braking surface of the rim.